ref: 6e3c739ea97108899f7bd7ccdcc6ae88afbf5efc
parent: d034ce85c420aba8bc635f1ce5541a8709112198
author: cinap_lenrek <cinap_lenrek@felloff.net>
date: Thu Aug 7 15:55:25 EDT 2014
pc64: fix wrong Ureg* argument on note handler (thanks _sl!) _sl reported crash: stats 593: suicide: sys: trap: fault write addr=0xffffffff8258d1b0 pc=0x204cc7 ; acid 593 /proc/593/text:amd64 plan 9 executable /sys/lib/acid/port /sys/lib/acid/amd64 acid: lstk() notejmp(ret=0x1,j=0x40ac90)+0x13 /sys/src/libc/amd64/notejmp.c:10 alarmed(a=0xffffffff8258d1b0,s=0x7ffffeffea58)+0x3f /sys/src/cmd/stats.c:718 notifier+0x3e /sys/src/libc/port/atnotify.c:15 acid: note how a in alarmed is a kernel address! the first Ureg* argument is passed to the note handler in the RARG (BX) register, which was not loaded when returning to userspace from syscall() thru forkret(). fix by returning thru noteret() from syscall().
--- a/sys/src/9/pc64/trap.c
+++ b/sys/src/9/pc64/trap.c
@@ -769,6 +769,7 @@
if(scallnr!=RFORK && (up->procctl || up->nnote)){splhi();
notify(ureg);
+ ((void**)&ureg)[-1] = (void*)noteret; /* loads RARG */
}
/* if we delayed sched because we held a lock, sched now */
if(up->delaysched)
--
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